Mottramite
Current inventory:  0 gems
 

  
Mottramite is named for an occurrence at Mottram St. Andrew, Cheshire, England. However, ore stockpiled at Mottram St. Andrew was likely mined from the nearby Pim Hill mine, Shrewsbury, Shropshire.

Discovered in 1876;   IMA status:  Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

PbCu(VO₄)(OH)

Lead Copper Vanadinate Hydroxide

Molecular Weight:

402.69 gm

Composition:

Vanadium

12.65 %

V

22.58 %

V₂O₅

Copper

15.78 %

Cu

19.75 %

CuO

Hydrogen

0.25 %

H

2.24 %

H₂O

Lead

51.45 %

Pb

55.43 %

PbO

Oxygen

19.87 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Vanadates

Strunz 8th Ed. ID:

7/B.27-30

Nickel-Strunz 10th Ed. ID:

8.BH.40

8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H₂O
H : With medium-sized and large cations, (OH,etc.):RO₄ = 1:1

Related to:

Adelite-Descloizite Group. Descloizite-Mottramite Series. The copper analogue of Descloizite.

Varieties:

Duhamelite

Synonyms:

Chileite, Cuprodescloizite, Cuprovanadinite, Psittacinite

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

As crystals, equant or dipyramidal {111}, prismatic [001] or [100], with {101}, {201}, many others, to 3 mm, in drusy crusts, botryoidal, usually granular to compact, massive.

Twinning:

None

Physical Properties

Cleavage:

None observed

Fracture:

Small Conchoidal to Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

3.0 - 3.5, somewhat harder on crystal surfaces

Density:

~ 5.90 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Readily soluble in acids.

Optical Properties

Color:

Grass-Green, Olive-Green, Yellow-Green, Siskin-Green, Blackish Brown, nearly Black. Crystals often exhibit zonal growth with varying colours.

Transparency:

Transparent to nearly Opaque

Luster:

Greasy

Refractive Index:

2.170 - 2.320  Biaxial  ( - )

Birefringence:

0.120 - 0.150

Dispersion:

Strong;  r > v, rarely r < v

Pleochroism:

Visible. Weak to Strong; X = Y = canary-yellow to greenish yellow; Z = brownish yellow. Orientation: X = c; Y = b; Z = a

Occurances

Geological Setting:

A secondary mineral in the oxidized zone of vanadium-bearing base metal deposits.

Common Associations:

Descloizite, Duftite, Mimetite, Wulfenite, Cerussite, Azurite, Dioptase

Common Impurities:

Zn

Type Locality:

Mottram St Andrew, Cheshire, England, UK

Year Discovered:

1876

View mineral photos:

Mottramite Mineral Photos and Locations

More Information

Mindat.org 
Webmineral.com

Mottramite is a rare lead, copper, vanadinate mineral that is rarely available as a faceted gem. It is usually opaque black and found as minute crystals to 3 mm or druzy crusts. Transparent crystals large enough for faceting are very rare. Mottramite is an end member of the Mottramite-Descloizite series. Mottramite is the copper rich end member while Descloizite is the zinc rich member. Both minerals usually contain significant percentages of both elements and are rarely pure. One of the few lacalities for gem quality crystals is the Bookcliffs, Mesa County, Colorado, USA.

Non gemmy specimens are available from many localities: from Mottram St. Andrew, Cheshire, England. In the USA, at the Mammoth-St. Anthony mine, Tiger, Pinal County, from Bisbee, Cochise County, at the Total Wreck mine, Pinal County, in the Apache mine, near Globe, and from the 79 mine, near Hayden, Gila County, Arizona; at the Mayflower mine, Socorro Peak district, Socorro County, New Mexico; from the Whale mine, Goodsprings district, Clark County, Nevada. At Mina Grande, Arqueros, Coquimbo, Chile. Abundant at Tsumeb and elsewhere in the Otavi district, Namibia. At Kabwe (Broken Hill), Zambia.
 

  
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